1. Field of the Invention
The present invention relates to a tape drive unit and to a recording medium.
2. Description of the Related Art
A so-called xe2x80x9ctape streaming drivexe2x80x9d is known as a drive unit for recording/reproducing digital data on/from a magnetic tape. This tape streaming drive can have a large recording capacity of, for example, approximately several dozen to several hundred gigabytes, although the capacity varies according to the length of the tape (as a medium) in the tape cassette. Accordingly, the tape streaming drive has various uses, such as a backup of data recorded on a medium such as a hard disk for a computer. The tape streaming drive is suitable for storing image data, which is typically large.
As the above-described tape streaming drive, one that performs data recording/reproduction by employing a helical scan system using a rotary head and using, for example, an 8-mm videocassette-recorder (VCR) tape cassette as a recording medium, has been proposed.
A tape streaming drive using an 8-mm VCR tape cassette, as described above, uses, for example, a small computer system interface (SCSI) as an input/output interface for recording/reproduced data.
In the recording mode, data supplied from, for example, a host computer, are input via the SCSI. Predetermined compression and encoding processes on the input data are performed and the processed data are recorded on a magnetic tape in a tape cassette.
In the reproducing mode, the data on the magnetic tape are read and decoded. The decoded data are transmitted to the host computer via the SCSI.
In data storage systems comprised of the tape streaming drive, the host computer, and the tape cassette, one has been developed that includes a nonvolatile memory in the tape cassette and stores, in the nonvolatile memory, various types of management information related to the operations of recording and reproduction on the magnetic tape.
In the nonvolatile memory, a terminal for an interface is formed on the tape cassette and is connected to a corresponding terminal of the tape streaming drive when the tape cassette is loaded. This enables the tape streaming drive to access the nonvolatile memory.
In the nonvolatile memory, for example, tape-cassette manufacturing information, use-record information, on-magnetic-tape partition information, etc., are recorded as management information. By storing the management information in the nonvolatile memory, the efficiency of various operations is highly increased compared with the recording of the management information in a specific region on the magnetic tape. That is, the need to run the tape to write and read the management information is eliminated, greatly shortening the time required for reading and updating the management information. In other words, the writing and reading of the management information can be performed regardless of the position on the magnetic tape and the operation status. In addition, this broadens the application range of the management information and enables various and effective control processes.
In the case where the tape streaming drive acquires required information by accessing the nonvolatile memory, data communication is performed in units of required data lengths at a clock frequency. In the case where such data transfer is performed, communication is possible when, for example, a data-communicatable data-length unit, a clock frequency, and so forth (the data-length unit and the clock frequency, etc., are hereinafter referred to as the xe2x80x9ccommunication methodxe2x80x9d), as tape-streamer-drive performance, are equivalent to or less than the communication method of the nonvolatile memory of the tape cassette. Therefore, in the tape streaming drive, it is preferable to set the data-length unit to be shorter and the clock frequency to be slower in order to maintain compatibility with a tape cassette including a nonvolatile memory having a communication method of differing performance.
When the communication method is set using a short data-length unit and a slow clock frequency in the tape streaming drive, compatibility with plural types of tape cassettes can be obtained. However, in the case where a tape cassette includes a nonvolatile memory having a communication method of higher performance than that of the tape streaming drive, the tape streaming drive cannot perform the communication method reliably. In other words, the communication method of the tape streaming drive limits the amount of information which can be transferred at one time. Thus, for the reading/writing of relatively large amounts of data, data transfer must be performed plural number of times.
Therefore, a problem occurs in that, for a nonvolatile memory having high performance, operations adapted for its communication method cannot be performed, hindering efficient reading/writing of data.
Accordingly, it is an object of the present invention to provide a tape drive unit and a recording medium in which data is efficiently read/written by performing operations adapted for a communication method.
To this end, according to an aspect of the present invention, the foregoing object is achieved through provision of a tape drive unit including a tape drive unit for recording or reproducing information on or from a magnetic tape when a tape cassette including the magnetic tape is loaded, a memory drive unit for reading or writing management information by performing communication with a memory for managing recording to or reproduction from the magnetic tape when the loaded tape cassette includes the memory, a detecting unit for detecting data-transfer information on the memory which is stored in the memory, and a setting unit for setting, based on the data-transfer information, the communication method of the memory drive unit.
Preferably, the data-transfer information includes unit-data information and clock-frequency information used when the memory performs data communication with the memory drive unit.
The communication method setting unit may set the memory drive unit to be in initial condition before the data-transfer information is detected.
In the initial condition, the lowest clock frequency and the shortest unit-data length which can be set by the memory drive unit may be set.
According to another aspect of the present invention, the foregoing object is achieved through provision of a recording medium including a tape cassette including a magnetic tape, and a memory, included in the tape cassette, which stores management information for managing recording to or reproduction from the magnetic tape, wherein data-transfer information on the memory is stored in the memory.
Preferably, the data-transfer information includes unit-data-length information and clock-frequency information used when data communication is performed with a memory drive unit in a tape drive unit into which the recording medium is loaded.
According to the present invention, a tape drive unit uses efficient data transfer to enable the reading or writing of management information by fully using the performance of the memory.
In addition, since data-transfer information is stored in the memory in the recording medium, whenever the recording medium is loaded into the tape drive unit, the tape drive unit can detect its data-transfer information from the memory. In other words, the data transfer information can be supplied to the tape drive unit adapted for the memory.
Moreover, the tape drive unit can detect, as the data transfer information, data-length-unit information on transfer data from the memory and clock-frequency information at the time of data transfer. Accordingly, the tape drive unit can perform accessing, using a maximum data-length unit of the memory, and can perform data reading or writing at a greatly high speed, using a maximum clock frequency.
FIG. 1 is a block diagram of a tape streaming drive according to an embodiment of the present invention;
FIG. 2 is a schematic illustration showing the internal structure of a tape cassette according to an embodiment of the present invention;
FIG. 3 is a perspective view showing the exterior of the tape cassette shown in FIG. 2;
FIG. 4 is an illustration showing the structure of data in the MIC 4 shown in FIG. 2;
FIG. 5 is an illustration of the manufacture information shown in FIG. 4;
FIG. 6 is an illustration of the memory management information shown in FIG. 4;
FIG. 7 is an illustration of the volume tag shown in FIG. 4;
FIG. 8 consists of illustrations of a cell structure in the MIC 4 shown in FIG. 2;
FIG. 9 is a block diagram showing an outline of data communication between the system controller 15 and the MIC 4 shown in FIG. 1; and
FIG. 10 is a flowchart illustrating a process for setting, based on data transfer information stored in the MIC 4 according to an embodiment of the present invention, the communication method of the tape streaming drive 10 according to another embodiment of the present invention.